Flip chip ball grid array with low impedence and grounded lid

ABSTRACT

A contact spring for placement in a gap between an electrical substrate opposite a lid (electrically conductive heat spreader) of an electronic device comprises a spring that both conducts heat from the substrate to the lid and electrically connects the substrate and lid. The spring comprises a flat single element configured as a plurality of polygons, providing contact points, the spring substantially lying in a plane and extending substantially in a straight line, or a spiral. The spring in an electronic device such as a flip chip ball grid array having this lid and an electrical substrate with EMI emitters: (1) provides low impedance electrical connection between the electronic circuit and lid; (2) grounds the lid to the electronic circuit; (3) minimizes EMI in the electronic circuit; (4) conducts heat from the electronic circuit to the lid; or any one or combination of the foregoing features (1)-(4).

This application is a continuation of parent application Ser. No.15/275,248 Filed Sep. 23, 2016 which is incorporated herein by referencein its entirety. Applicants claim all benefits of this parentapplication pursuant to 35 USC § 120.

FIELD OF THE INVENTION

The field of the invention comprises, inter alia, a flip chip ball gridarray (FCBGA) with low impedance and a grounded lid.

BACKGROUND OF THE INVENTION

Semiconductor packages are becoming stronger EMI (electromagneticinterference) emitters within an electronic system because chipoperating frequencies and power are increasing. In order to ensurecompliance to international standards for EMC (electromagneticcompatibility), system designers must work with electronic packagingdesigners of the various subsystems: power supplies, motors, cableinterconnection, printed circuit board and chip modules. These severaldesigners must identify the strong

EMI emitters and proactively apply EMI mitigation practices. One area ofincreasing focus is the high speed, highly integrated semiconductorpackage. On chip currents and voltages create magnetic and electricfields that travel through free space. These stray electro magnetic (EM)fields can adversely interact with other assemblies within the systemand also, can leak through system cabinet seams, openings and vents. EMemissions from chips can be intercepted by an electrically conductivethe heat spreader or lid that is typically adhesively bonded directly tothe back side of a flip chip and the heat spreader is electricallygrounded.

One practice has been to use metal clips that are installed on thefinished module or after the module has been attached to a printedcircuit card or board. The clip electrically and mechanically links theelectrically conductive heat spreader to a ground pad either on the chipsubstrate or directly to the card, i.e., the chip package. Clipinstallation is difficult to automate and also has the potential tocreate metal debris from scraping. Since the clips protrude beyond thestandardized physical outline of the package, forethought might berequired during the card or board design to allow extra space forinstallation. A more preferred grounding solution is one that can beeasily incorporated during the chip package manufacturing. Solderinterconnection has been evaluated and found to be sensitive to fatiguecracking. Solder connects the underside of the electrically conductiveheat spreader to ground pads on the substrate.

These connections are short in length and exposed to package shear andtensile cyclic stresses from heating and cooling that eventually resultin cracked solder joints. An alternative to solder is electricallyconductive adhesive (ECA) joining which provides a more strain/stresstolerant connection. However, ECAs require noble metal finishes for lowcontact resistance that is stable through environmental stress. Nonnoble finishes such as nickel and copper might provide low contactresistance just after bonding but are subject to continued oxidation andhydration that leads to high resistances in the several ohm range.Further, ECA cure chemistry has been known to adversely interfere withthe cure chemistry of sealband adhesives that are used to bond theelectrically conductive heat spreader to the substrate. ECA joints arevulnerable to degradation during impact shock loading.

RELATED ART

The following references relate to the state of the art in the field ofthe invention:

United States Patent and Patent Applications, U.S. Pat. No. 3,747,044;20140378008; 20100279558; U.S. Pat. Nos. 8,363,411; 7,999,202;7,914,351; 6,744,269;

Chinese; CN205248253U; CN104684329A;

German; DE202015105765U1; DE102008045615B4;

Japanese JP2014225571A.

SUMMARY OF THE INVENTION

The present invention provides structures, articles of manufacture andprocesses that address these needs, and products produced by theseprocesses that not only provide advantages over the related art, butalso to substantially obviate one or more of the foregoing and otherlimitations and disadvantages of the related art. Not only do thewritten description, claims, abstract of the disclosure, and thedrawings, that follow set forth various features, objectives andadvantages of the invention and how they may be realized and obtained,but these features, objectives and advantages of the invention will alsobecome apparent by practicing the invention.

To achieve these and other advantages, and in accordance with thepurpose of the invention as embodied and broadly described herein, theinvention comprises the use of an electrical contact spring in the gapbetween a lid also referred to as a electrically conductive heatspreader and an electronic device substrate, i.e., electrical substrate,such as a flip chip substrate. A contact spring is a continuous, fatigueresistant metal such as BeCu that has compliance to accommodate shearand tensile package stresses. The contact spring has a plurality ofdevice contacts in the body of the spring where the device contactsextend from one side edge of the spring or one surface of the spring, orboth the side edge and the surface, the device contacts being arrangedso that they are operatively associated with the

electrically conductive heat spreader and the electrical substrate,e.g., at least one device contact point can abut up against theelectrically conductive heat spreader and at least one device contactpoint can abut up against the electrical substrate. In the embodimentwhere we configure the contact spring as a flat oblong, it will havemore than one device contact along its length.

The contact spring can be soldered, mechanically loaded, or adhesivelyjoined to the device, or used in any combination of these processes, allof which comprise a way to operatively associate the electrical contactspring in the gap of the device with the lid and the substrate to obtainheat conductance from the substrate to the lid, EMI reduction, agrounded lid and low impedance in the electronic device.

The contact spring for placement in a gap between an electricalsubstrate juxtaposed opposite a lid or electrically conductive heatspreader of an electronic device comprises a spring that both conductsheat from the substrate to the lid and electrically connects thesubstrate and lid through device contacts on the spring. The spring inthis respect is operatively associated with the lid and the electricalsubstrate. The spring comprises a flat single element but configured asa plurality of polygons, to provide one or multiple device contacts, thespring substantially lying in a plane and extending substantially in astraight line, or a spiral.

In another embodiment, placing the spring this way in an electronicdevice such as a flip chip ball grid array having a lid (electricallyconductive heat spreader) and an electrical substrate that includes EMIemitters: (1) provides a low impedance electrical connection between theelectrical substrate and the lid; (2) grounds the lid to the electricalsubstrate; (3) minimizes EMI in the electrical substrate; (4) conductsheat from the electrical substrate to the lid, or any one or combinationof the foregoing properties (1)-(4). Additionally, placing the spring inthis way in an electronic device to obtain any one or combination of theforegoing properties, also produces an article of manufacture in whichthe spring is operatively associated with the lid and the electricalsubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are not necessarily drawn to scale butnonetheless set out the invention, and are included to illustratevarious embodiments of the invention, and together with thisspecification also serve to explain the objects, advantages, andprinciples of the invention. The drawings comprise:

FIG. 1A comprises a side elevation in cross-section of a planar or leafspring of this invention;

FIG. 1B comprises a plan view of a planar or leaf spring of thisinvention;

FIG. 1C comprises an end elevation taken along line 3-3 of FIG. 1B;

FIG. 1D comprises an end elevation taken along line 1-1 of FIG. 1A andFIG. 1B;

FIG. 1E comprises a partial cross-section taken along line 2-2 of FIG.1B;

FIG. 2 comprises a side elevation in cross-section of a planar or leafspring of this invention;

FIG. 3 comprises a side elevation in cross-section of a planar or leafspring of this invention;

FIG. 4 comprises a perspective view of a type of planar or leaf springof this invention;

FIG. 5 comprises a side elevation in cross-section of a planar or leafspring of this invention operatively associated with an electronicdevice having a substrate and electrically conductive heat spreader;

FIGS. 6A, 6B, 6C, and 6D, comprise side elevations in cross-section ofthe planar spring of the present invention configured to spiral aroundan axis fixed in space.

FIG. 6E comprise a plan view of the spring of FIG. 6D.

DETAILED DESCRIPTION

To achieve these and other advantages, and in accordance with thepurpose of this invention as embodied and broadly described herein, thefollowing detailed embodiments comprise disclosed examples that can beembodied in various forms. The specific processes and structural detailsset out comprise a basis for the claims and a basis for teaching oneskilled in the art to employ the present invention in any novel anduseful way. The terms, phrases and Figures

also set out herein provide a description of how to make and use thisinvention. One having ordinary skill in the relevant art, once aware ofthe present disclosure, could employ suitable processes and structureswithout undue experimentation.

In one aspect, the invention comprises a spring design concept shown inthe various FIGS., described above. The spring typically is longer thanit is wide, e.g., having any where from about 2 to about 50 times itswidth, about 2 to about 40 times its width, about 2 to about 20 timesits width, or from about 2 to about 10 times its width and the like.

FIG. 1 A, as noted, comprises a side elevation in cross-section of aplanar or leaf spring 10 of this invention made from an alloy BeCuoptionally plated with a metal such as Sn, e.g., by an immersion tincoating process known in the art, or any of the noble metals such as Au,Pt, Ir, Os, and Re. One end of spring 10 bends away from the body of thespring and turns downward at the end of the bend to form a contact edgeshown in the FIG. 1D head on view or end elevation taken along line 1-1of FIG. 1A and FIG. 1B. FIG. 1D also shows spring 10 in one embodimentas an arced planar element, i. e., spring 10 is arced along its width,as also shown in FIG. 1C, an end elevation taken along line 3-3 of FIG.1B. FIG. 1B comprises a plan view of spring 10, and also illustrates adimple 12 extending outwardly from spring 10, as well as perforations 13and 14 on spring 10. FIG. In another embodiment, not illustrated, spring10 may have up to about five, or up to about ten dimples like dimple 12.We consider the surface of the spring 10 at the base of dimple 12 as itextends outwardly and away from the base of dimple 12 as a second devicecontact, and dimple 12 as a first device contact so that the surface ofspring 10 at this point has more than one contact point. 1E comprises aside elevation in cross-section taken along the line 2-2 of FIG. 1Billustrating the projection of dimple 12 outwardly from the surface ofspring 10. The flexibility of spring 510 allows it to be bentsubstantially up to about 180° so that it may be operatively associatedwith groove 523 in lid 516.

In FIG. 2, and FIG. 3 we illustrate a side elevation in cross-section ofa planar or leaf spring 20 or 30 of this invention, fabricated of thesame material of, and optionally plated in the same way as spring 10. Inboth FIG. 2 and FIG. 3 we provide multiple ground connection points toreduce inductance. The spring 20 can be formed so that both ends havecontact tips 22 and 24 pointing away from spring 20, or multiple devicecontacts as shown in FIG. 3 that illustrates mild bends in the spring 30to have as many device contacts as needed. FIG. 3 in this regard depictseight upper device contacts and nine lower device contacts pitched at0.125 inches along a one inch length. The bending shown here is a seriesof kinks forming line-type device contacts across the width of thestrip.

Another embodiment of the invention comprises the bends in spring 40illustrated in FIG. 4 comprising twists of the spring into bow tieshapes along the length of the strip thereby providing multiple contactsat smaller regions along the side edges of the strip. Yet anotherembodiment would be cone shaped, split washer springs 660(Belleville-like springs as disclosed herein, with an embodimentillustrated in FIGS. 6D and 6E)) placed at intervals along the seal band517A (not illustrated).

FIG. 5 comprises a side elevation in cross-section of a planar or leafspring of this invention operatively associated with an electronicdevice having a substrate and electrically conductive heat spreader.FIG. 5, illustrates a typical flip chip electronic ball grid array(FCPBGA) package 510 that includes Chip 511 having a plurality of solderbumps 512 for connecting to corresponding pads (not shown) on a surfaceof substrate 513. Solder balls 514 are provided on the underside ofsubstrate 513 in order to attach the package to other circuitry on asubstrate or circuit board. Chip 511 is electrically connected by meansof the chip solder bumps 512 and conductive circuitry through substrate513 to solder balls 514 in a well known manner. Chip 511 is sealed tosubstrate 513 by underfill 515 and optionally other encapsulatingmaterial known in the art. Cover plate or lid 516 (which also functionsas a electrically conductive heat spreader, and which may be constructedfrom Cu) extends outwardly over a gap that contains contact spring 521,flexed from a substantially flat configuration to any where from about10° to about 180°, and is attached to the upper surface of chip 511 asshown, by means of thermally conductive adhesive 517. Typically, a firstadhesive 517 is applied to the upper surface of chip 511, and a secondadhesive 517A (i.e., a seal band) is applied on the upper surface of thesubstrate 513 at its perimeter. Lid 516 is placed thereon and theadhesive subsequently cured. Lid 516 provides physical protection forchip 511 and also in conjunction with the thermally conductive adhesive517 acts as an electrically conductive heat spreader to dissipateunwanted heat that is generated by the electronic device or chip 511.Good thermal conductivity between chip 511 and lid 516 requires adhesive517 to be in the form of a relatively thin and uniform adhesive bondline between lid 516 and chip 511.

Ground pad 518 as shown, for example, on the upper surface of substrate513, is electrically connected to ground potential as by circuitrythrough substrate 513 to one or more solder balls 514, as is well known.

The existence of one or more openings 520 in lid or cover 516 providesfor various forms of electrical and physical connections between lid 516and ground pad 518. According to one embodiment of the present inventionwe provide the electronic package 510 with a more compliant connectionbetween lid 516 and one or more ground pads 518 than what is achievablewith a fixed adhesive or solder connection as previously described. Weplace contact spring 521 of the present invention in a gap betweenelectrically conductive heat spreader 516 and substrate 513 whichcomprises an electrical substrate as shown in FIG. 5.

Contact spring 521 of the present invention comprises a flat singleelement but configured as a plurality of polygons joined to one anotherone edge to one edge to form a pattern of repeating polygonssubstantially lying in a plane and extending substantially in a straightline, the length of the contact spring being greater than its width. Wealso refer to contact spring 521 as a leaf spring, but also configure itas a spiral connector. We fabricate contact spring 521 out of springmaterials such as Be/Cu that may be coated with tin, e.g., by means of atin immersion coating or tin electroplating, or a coating comprising aprecious metal such as gold.

These polygons comprise three or four sided polygons or polygons havingup to about ten or more sides where the polygons having three, five or agreater number of sides provide multiple device contacts along one orboth of the side edges (i.e., the non-joined polygon edges) of thecontact spring. These polygons comprise triangles, squares, any otherparallelograms, e.g., rectangles, as well as trapezoids, rhombi,pentagons, hexagons, septagons, octagons or any other polygons having upto about ten sides, or more and the like known in the art. FIG. 1Aillustrates a configuration of the spring that projects the joining ofsquares edge to edge in substantially a straight line, whereas FIG. 4illustrates a configuration of the spring that projects the joining ofpolygons, i.e., squares and triangles edge to edge to provide multipledevice contacts along at least one of the side edges (i.e., thenon-joined edges) of the spring as it projects in substantially astraight line from the first of the polygons to the last of thepolygons.

We place contact spring 521 in opening 520 of lid 516 where the opening520 has been designed to be physically located proximate to the area ofthe corresponding ground pad 518 on substrate 513 during the attachmentof lid 516 to chip 511. By providing contact spring 521 withpre-soldered regions at each extremity thereof, contact spring 521 canbe readily soldered to either lid 516 or ground pad 518 or both as shownby connectors 522 (e.g., solder connectors) during the subsequent solderflow process of attaching solder balls 514 to the substrate 513 orcircuit board. The attachment of spring contact 521 in this mannermaintains compliance between the two connectors 522. With the approachas described for this aspect of the embodiment of the invention, minimalpre-alignment, pre-placing or pre-solder attachment is required betweencontact spring 521 and lid 516. In addition, no pressure is required tobe applied between lid 516 and substrate 513 to ensure contact spring521 appropriately contacts lid 516 and ground pad 518 during theattachment of lid 516 to chip 511 since the placement of contact spring521 and the soldering of contact spring 521 to lid 516 and ground pad518 is achieved subsequent to and separate from the process ofattachment of cover 516 to chip 511. Furthermore, there is no adverserequirement, for example, to blindly align contact spring 521 to groundpad 518 from the bottom surface of cover 516 as the connection isvisible from the top of opening 520.

Connectors 522 may comprise electrical conductor and heat conductor,i.e., electrically conductive heat spreader materials such as metalconnectors extending from and operatively associated with ground pad518. Connectors 522 include solder connectors In one embodiment wherecontact spring 521 of the present invention comprises a leaf spring thathas been dimpled with dimple 12, we provide groove 523 in lid 516 thatis arranged to conductively engage dimple 12, i.e., electrically and/orthermally engage dimple 12, and improve electrical connectivity and heatconductivity of contact spring 521 with lid 516, connectors 522, solderbumps 512, substrate 513, underfill 515, and chip 511.

FIGS. 6A, 6B, 6C, 6D, and 6E comprise side elevations in cross-sectionof the planar spring of the present invention shown in FIGS. 1A, 1B, 2,3, and 4, configured to spiral around an axis 66 fixed in space. FIG. 6Acomprises a tubular configuration, FIG. 6B, a conical configuration, andFIG. 6C, a frusto-conical configuration.

FIG. 6E comprises a side elevation in cross-section of a planar spring660, configured after the spring of FIG. 1A spiraling around an axis 66fixed in space to form a split washer, a Belleville-like washer, wherethe plane of the spring only spirals about one time around axis 66 byabout 360° and the plane of the spring terminates in ends 670 and 680.

FIG. 6F comprises a plan view of the article illustrated in FIG. 6E.

In another embodiment planar spring 660 may be configured to spiralaround an axis fixed in space to form a split Belleville-like washerwhere the plane spirals around an axis fixed in space a number ofdegrees comprising about 340° to about 380°.

In use, the spring 10 as illustrated in FIG. 1A to FIG. 1 E having a lowprofile that allows it to work in the typically practiced sealbandbondline space, and typically about two to about five mm wide and about0.15 mm to about to about 0.3 mm tall (about 0.006 inches to about 0.012inches). The spring 10 is press fit into a groove or slot 523 of thedevice shown in FIG. 5 that is machined into the lid or electricallyconductive heat spreader 516. A dimple 12 is formed on the spring 10.When pressed into the heat spreader groove 523 with about <10 lbs, thechord length decreases allowing insertion and scraping between a tangenton the dimple and the sidewall of the groove 523. The dimple 12 ismechanically locked into the groove 523 and provides a contactresistance. The contact shaft which can be narrower (not shown) than thepress fitted dimple 12 is recessed into the groove 523 and thus, is notin the sealband bondline space. The dimple can be positioned along theshaft to define low deflection forces (25-125 grams) for the contacttips (line 1-1 and line 3-3 of FIG. 1B) which also has a hemisphericaldimple (FIG. 1D) that lands on the ground ring of the chip carrierduring heat spreader attachment. There are several options for treatingthe contact tips. Contact spring 10, when made of BeCu, the easiestoption is to do nothing to the BeCu surface or to have it pretreatedwith a copper passivation such a benzotriazole. Typically, a ground pad518 on the carrier 513 will be covered with solder. During the normalmanufacturing solder reflows, subsequent to lid 516 attach, the solderalloy on the pad will reflow and metallurgically wet the BeCu spring.Alternatively, the contact tips (line 1-1 and/or line 3-3 of FIG. 1B)can be plated with Sn e.g., by immersion coating, or a lead free alloywhich will facilitate metallurgical joining to the carrier ground padduring reflow to ensure a low and stable contact resistance connection.Lastly, noble metal plating can be used at both the contact tip andcarrier pad.

In the process sequence for heat spreader attachment, we would formgrove 523 in the lid or electrically conductive heat spreader 516 beforeplating with Ni whereas the current process can also involve Ni platingwithout forming groove 523. We would then insert springs 10 into thegroove 523 in a manner previously described and the lid 516 would beready to be combined with the device 510. By contrast, in the existingprocess steps, the sealband adhesive is dispensed on the chip carrierleaving openings around the ground pads to which springs are placed tomake contact with the chip carrier, the lid is placed on the resultantassembly, a mating force applied, the structure is locked and the cured.

Another embodiment comprises the bends in spring 40 illustrated in FIG.4 comprising twists of the spring into bow tie shapes along the lengthof the strip thereby providing multiple contacts at smaller regionsalong the side edges of the strip. Yet another embodiment would be coneshaped washer springs (e.g., Belleville-like springs, 600 illustrated inFIGS. 6-D, 6-E or cone shaped springs FIGS. 6B, 6C) placed at intervalsalong the seal band.

With these concepts, it is possible to eliminate the heat spreadergrooving. A portion of the seal band adhesive would be dispensed inlines, line segments or dots. After placing the strips along each edgeof the carrier 513 and into the sealband adhesive, more sealbandadhesive is dispensed to primarily fill the valley bends shown in FIG.3. An alternative is to punch holes in the strip length that allow theinitial deposit of adhesive to pass through. Next, place aplan-of-record lid and cure under force. The peaks and valleys of thebends will push through the adhesive and contact the lid and ground padsfor metal-to-metal contact. Similar structures have been prototyped andyield low and stable contact resistance (<20 milliohms) throughenvironmental stress that would be more than adequate to meet therequirements defined by OEM.

Various embodiments of our invention also comprise inter alia a processfor manufacturing an article of manufacture comprising placing a contactspring for placement in a gap between a electrically conductive heatspreader and an electrical substrate, the heat spreader positioned toremove heat from the electrical substrate, the spring being structuredto both conduct heat from the substrate to the heat spreader and toelectrically connect the substrate and heat spreader, the springcomprising a flat single element but configured as a plurality ofpolygons joined to one another, one edge of one polygon to one edge of acontiguous polygon to form a pattern of repeating polygons substantiallylying in a plane and extending substantially in a straight line, thelength of the contact spring being greater than its width, the contactspring comprising one or multiple device contacts that extend at leastfrom one side edge of the spring, or greater than three device contactsthat extend from at least one surface of the spring, the device contactsarranged so that the spring comprises at least one device contact thatabuts up against the heat spreader and at least one device contact thatabuts up against the electrical substrate. In further embodiments, eachof the polygons may have the same number of sides, e.g., from three toabout four sides; the plane may project forwardly along its length, andthen at one interval or a plurality of intervals along its length,extends upwardly for a fixed number of degrees and subsequentlydownwardly for about the same number of degrees to form the devicecontacts and the plane continues to project forwardly along its length;at least one of the intervals may be separated by the plane thatcontinues to project forwardly along its length; the plane may be arcedalong its length to form one of the device contacts; the plane may bedimpled to form at least one of the device contacts, the dimpleconductively engaging a groove in at least one of the electricallyconductive heat spreader or electrical substrate to provide a heatconductive contact and electrical contact between the article, theelectrically conductive heat spreader, and the electrical substrate; oneor both ends of the plane may be angled away from the plane to form thedevice contacts; both ends of the plane may be angled away from theplane in the same direction; the plane may have an arced cross section.

The foregoing process may also comprise forming said contact spring tocomprise a combination of different polygons arranged to provide severalof the device contacts along at least one of the non-joined side edgesof the polygons and functioning as the device contacts as the springprojects forward from the first of the polygons to the last of thepolygons, and in one further embodiment may be substantially as shown inFIG. 4; and in another embodiment, the plane is optionally perforated.

Various other embodiments of our invention also comprise inter alia aprocess for producing an article of manufacture comprising placing acontact spring in a gap between an electrically conductive heat spreaderand an electrical substrate, the heat spreader positioned to remove heatfrom the electrical substrate, the spring being structured to bothconduct heat from the substrate to the heat spreader and to electricallyconnect the substrate and heat spreader, the spring comprising a flatsingle element but configured as a plurality of polygons joined to oneanother, one edge of one polygon to one edge of a contiguous polygon toform a pattern of repeating polygons substantially lying in a plane thatspirals around an axis fixed in space, the length of the contact springbeing greater than its width, the contact spring having multiple devicecontacts in the body of the spring where the device contacts extend fromone side edge of the spring or one surface of the spring, or both theside edge and the surface, the device contacts arranged so that at leastone abuts up against the heat spreader and at least one can abut upagainst the electrical substrate. In further embodiments each of thepolygons may have the same number of sides; each of the polygons mayhave from three to about four sides; the polygons may have from three toabout four sides; the plane projects forwardly along its length, andthen at one interval or a plurality of intervals along its length,extends upwardly for a fixed number of degrees and subsequentlydownwardly for about the same number of degrees to form the devicecontacts and the plane continues to project forwardly along its length;at least one of the intervals may be separated by the plane thatcontinues to project forwardly along its length; one or both ends of theplane may be angled away from the plane to form the device contacts;both ends of the plane may be angled away from the plane in the samedirection; the plane in profile may spiral around an axis fixed in spaceto form a tubular shape; the plane in profile may spiral around an axisfixed in space to form a frusto-conical shape; the plane may have anarced cross section; the repeating polygons that extend upwardly anddownwardly around the axis fixed in space may have an inner edge facingthe axis and an outer edge facing away from the axis, and the inner edgeand the outer edge are rounded toward the axis; the article ofmanufacture may be configured as a split washer where the plane onlyspirals about once around the axis; the article of manufacture may beconfigured as a split washer where the plane spirals around the axis byabout 340° to about 380°;

Various embodiments of our invention as set out in paragraph [0030.3]also comprise inter alia a process for manufacturing an article ofmanufacture where the contact spring that may be positioned in anelectronic device having an electronic circuit that includes EMIemitters, the electronic device also including a lid comprising asubstantially juxtaposed electrically conductive heat spreader, thecontact spring operatively associated with the electronic circuit to atleast: (1) provide a low impedance electrical connection between theelectronic circuit and the lid; (2) ground the lid to the electroniccircuit; (3) minimize EMI in the electronic circuit; (4) conduct heatfrom the electronic circuit to the lid; or any one or combination of thefeatures (1), (2), (3), (4); the electronic device may comprise a flipchip ball grid array; each of the polygons may have the same number ofsides; each of the polygons may have from three to about four sides; theplane may project forwardly along its length, and then at one or aplurality of intervals along its length, extends upwardly for a fixednumber of degrees and subsequently downwardly for about the same numberof degrees and the plane continues to project forwardly along itslength; at least one of the intervals may be separated by the plane thatcontinues to project forwardly along its length; the plane may bedimpled to form at least one of the device contacts, the dimple arrangedto conductively engage a groove in at least one of the electricallyconductive heat spreader or electrical substrate to provide a heatconductive contact and electrical contact between the article, the heatspreader, and the electrical substrate; one or both ends of the planemay be angled away from the plane to form the device contacts; both endsof the plane may be angled away from the plane in the same direction;the plane may have an arced cross section; the article of manufacturemay comprise a combination of different polygons arranged to provideseveral of the device contacts along at least one of the non-joined sideedges of the polygons to act as the device contacts as the springprojects in substantially a straight line from the first of the polygonsto the last of the polygons; the spring may be configured substantiallyas shown in FIG. 4; the plane may be optionally perforated.

Throughout this specification, abstract of the disclosure, claims, andin the drawings the inventors have set out equivalents, includingwithout limitation, equivalent elements, materials, compounds,compositions, conditions, processes, structures, and even though set outindividually, also include combinations of these equivalents such as thetwo component, three component,

or four component combinations, or more as well as combinations of suchequivalent elements, materials, compounds, compositions conditions,processes, structures in any ratios or in any manner.

Additionally, the various numerical ranges describing the invention asset forth throughout the specification also includes any combination ofthe lower ends of the ranges with the higher ends of the ranges, and anysingle numerical value, or any single numerical value that will reducethe scope of the lower limits of the range or the scope of the higherlimits of the range, and also includes ranges falling within any ofthese ranges.

The terms “about,” “substantial,” or “substantially” as applied to anyclaim or any parameters in this written description, such as a numericalvalue, including values used to describe numerical ranges, means slightvariations in the parameter. In another embodiment, the terms “about,”“substantial,” or “substantially,” when employed to define numericalparameter include, e.g., a variation up to five per-cent, ten per-cent,15 per-cent, or 20 percent, or somewhat higher or lower than the upperlimit of five per-cent, ten per-cent, 15 per-cent, or 20 per-cent. Theterm “up to” that defines numerical parameters means a lower limitcomprising zero or a miniscule number, e.g., 0.001.

The terms “about,” “substantial” and “substantially” also mean thatwhich is largely or for the most part or entirely specified. Theinventors also employ the terms “substantial,” “substantially,” and“about” in the same way as a person with ordinary skill in the art wouldunderstand them or employ them. The phrase “at least” means one or acombination of the elements, materials, compounds, or conditions, andthe like specified herein, where “combination” is defined above. Theterms “written description,” “specification,” “claims,” “drawings,” and“abstract” as used herein refer to the written description,specification, claims, drawings, and abstract of the disclosure asoriginally filed, and if not specifically stated herein, the writtendescription, specification, claims, drawings, and abstract of thedisclosure as subsequently amended.

All scientific journal articles and other articles, including internetsites, as well as issued and pending patents that this writtendescription mentions including the references cited in such scientificjournal articles and other articles, including Internet sites, and suchpatents, are incorporated herein by reference in their entirety and forthe purpose cited in this written description and for all otherdisclosures contained in such scientific journal articles and otherarticles, including internet sites as well as patents and the aforesaidreferences cited therein, as all or any one may bear on or apply inwhole or in part, not only to the foregoing written description, butalso the following claims, abstract of the disclosure, and appendeddrawings.

Although the inventors have described their invention by reference tosome embodiments, other embodiments defined by the doctrine ofequivalents are intended to be included as falling within the broadscope and spirit of the foregoing written description, and the followingclaims, abstract of the disclosure, and appended drawings.

We claim:
 1. A process for manufacturing a device comprising placing acontact spring in a gap between a electrically conductive heat spreaderand an electrical substrate, said heat spreader positioned to removeheat from said electrical substrate, said spring being structured toboth conduct heat from said substrate to said heat spreader and toelectrically connect said substrate and heat spreader, said springcomprising a flat single element but configured as a plurality ofpolygons joined to one another, one edge of one polygon to one edge of acontiguous polygon to form a pattern of repeating polygons substantiallylying in a plane and extending substantially in a straight line, thelength of said contact spring being greater than its width, said contactspring comprising one or multiple device contacts that extend at leastfrom one side edge of said spring, or greater than three device contactsthat extend from at least one surface of said spring, said devicecontacts arranged so that said spring comprises at least one devicecontact that abuts up against said heat spreader and at least one devicecontact that abuts up against said electrical substrate.
 2. The processof claim 1 wherein each of said polygons have the same number of sides.3. The process of claim 1 wherein each of said polygons have from threeto about four sides.
 4. The process of claim 2 wherein said polygonshave from three to about four sides.
 5. The process of claim 1 whereinsaid plane projects forwardly along its length, and then at one intervalor a plurality of intervals along its length, extends upwardly for afixed number of degrees and subsequently downwardly for about the samenumber of degrees to form said device contacts and said plane continuesto project forwardly along its length.
 6. The process of claim 5 whereinat least one of said intervals is separated by said plane that continuesto project forwardly along its length.
 7. The process of claim 1 whereinsaid plane is arced along its length to form one of said devicecontacts.
 8. The process of claim 1 wherein said plane is dimpled toform at least one of said device contacts, said dimple conductivelyengaging a groove in at least one of said electrically conductive heatspreader or electrical substrate to provide a heat conductive contactand electrical contact between said article, said electricallyconductive heat spreader, and said electrical substrate.
 9. The processof claim 1 wherein one or both ends of said plane are angled away fromsaid plane to form said device contacts.
 10. The process of claim 9wherein both ends of said plane are angled away from said plane in thesame direction.
 11. The process of claim 1 wherein said contact springis formed to comprise a combination of different polygons arranged toprovide several of said device contacts along at least one of thenon-joined side edges of said polygons and functioning as said devicecontacts as said spring projects forward from the first of said polygonsto the last of said polygons.
 12. The process of claim 11 wherein saidcontact spring is substantially as shown in FIG.
 4. 13. The process ofclaim 1 wherein said plane is optionally perforated.
 14. A process formanufacturing a device comprising placing a contact spring in a gapbetween an electrically conductive heat spreader and an electricalsubstrate, said heat spreader positioned to remove heat from saidelectrical substrate, said spring being structured to both conduct heatfrom said substrate to said heat spreader and to electrically connectsaid substrate and heat spreader, said spring comprising a flat singleelement but configured as a plurality of polygons joined to one another,one edge of one polygon to one edge of a contiguous polygon to form apattern of repeating polygons substantially lying in a plane thatspirals around an axis fixed in space, the length of said contact springbeing greater than its width, said contact spring having multiple devicecontacts in the body of said spring where said device contacts extendfrom one side edge of said spring or one surface of said spring, or bothsaid side edge and said surface, said device contacts arranged so thatat least one abuts up against said heat spreader and at least one canabut up against said electrical substrate.
 15. The process of claim 14wherein each of said polygons has the same number of sides.
 16. Theprocess of claim 14 wherein each of said polygons have from three toabout four sides.
 17. The process of claim 15 wherein said polygons havefrom three to about four sides.
 18. The process of claim 14 wherein saidplane projects forwardly along its length, and then at one interval or aplurality of intervals along its length, extends upwardly for a fixednumber of degrees and subsequently downwardly for about the same numberof degrees to form said device contacts and said plane continues toproject forwardly along its length.
 19. The process of claim 18 whereinat least one of said intervals is separated by said plane that continuesto project forwardly along its length.
 20. The process of claim 14wherein said plane is arced along its length to form one of said devicecontacts.
 21. The process of claim 14 wherein said plane is dimpled toform at least one of said device contacts, said dimple conductivelyengaging a groove in at least one of said electrically conductive heatspreader or electrical substrate to provide a heat conductive contactand electrical contact between said article, said electricallyconductive heat spreader, and said electrical substrate.
 22. The processof claim 14 wherein one or both ends of said plane are angled away fromsaid plane to form said device contacts.
 23. The process of claim 22wherein both ends of said plane are angled away from said plane in thesame direction.
 24. The process of claim 14 wherein said plane inprofile spirals around an axis fixed in space forms a tubular shape. 25.The process of claim 14 wherein said plane in profile spirals around anaxis fixed in space forms a frusto-conical shape.
 26. The process ofclaim 14 wherein said repeating polygons that extend upwardly anddownwardly around said axis fixed in space have an inner edge facingsaid axis and an outer edge facing away from said axis, and said inneredge and said outer edge are rounded toward said axis.
 27. The processof claim 14 configured as a split washer where said plane only spiralsabout once around said axis.
 28. The process of claim 14 configured as asplit washer where said plane spirals around said axis by about 340° toabout 380°.
 29. The process of claim 1 wherein said contact spring ispositioned in an electronic device having an electronic circuit thatincludes EMI emitters, said electronic device also including a lidcomprising a substantially juxtaposed electrically conductive heatspreader, said contact spring operatively associated with saidelectronic circuit to at least: (1) provide a low impedance electricalconnection between said electronic circuit and said lid; (2) ground saidlid to said electronic circuit; (3) minimize EMI in said electroniccircuit; (4) conduct heat from said electronic circuit to said lid; orany one or combination of said features (1), (2), (3), (4).
 30. Theprocess of claim 29 where said electronic device comprises a flip chipball grid array.
 31. The process of claim 29 wherein each of saidpolygons has the same number of sides.
 32. The process of claim 29wherein each of said polygons has from three to about four sides. 33.The process of claim 29 wherein said polygons have from three to aboutfour sides.
 34. The process of claim 29 wherein said plane projectsforwardly along its length, and then at one or a plurality of intervalsalong its length, extends upwardly for a fixed number of degrees andsubsequently downwardly for about the same number of degrees and saidplane continues to project forwardly along its length.
 35. The processof claim 29 wherein at least one of said intervals is separated by saidplane that continues to project forwardly along its length.
 36. Theprocess of claim 29 wherein said plane is dimpled to form at least oneof said device contacts, said dimple arranged to conductively engage agroove in at least one of said electrically conductive heat spreader orelectrical substrate to provide a heat conductive contact and electricalcontact between said article, said heat spreader, and said electricalsubstrate.
 37. The process of claim 29 wherein one or both ends of saidplane are angled away from said plane to form said device contacts. 38.The process of claim 37 wherein both ends of said plane are angled awayfrom said plane in the same direction.
 39. The process of claim 29wherein said plane has an arced cross section.
 40. The process of claim29 comprising a combination of different polygons arranged to provideseveral of said device contacts along at least one of the non-joinedside edges of said polygons to act as said device contacts as saidspring projects in substantially a straight line from the first of saidpolygons to the last of said polygons.
 41. The process of claim 29 wheresaid spring is configured substantially as shown in FIG.
 4. 42. Theprocess of claim 29 wherein said plane is optionally perforated.